Solid aluminum electrolytic capacitor with good stability and preparation method thereof

Abstract

A solid aluminum electrolytic capacitor with good stability comprises a core package and a shell, the core package is arranged in the shell in a sealed mode through a rubber plug, the core package is formed by winding an anode foil, a cathode foil and electrolytic paper, and a conductive high-molecular polymer is formed between the anode foil and the cathode foil. The conductive high-molecular polymer comprises a first conductive high-molecular polymer layer and a second conductive high-molecular polymer layer, the first conductive high-molecular polymer layer comprises a first conductive high-molecular polymer and carbon microspheres wrapped with MnO2, and the carbon microspheres wrapped with MnO2 are wrapped with the first conductive high-molecular polymer. According to the invention, the carbon microspheres coated with MnO2 are added into the first conductive high-molecular polymer layer, so that a supporting effect can be achieved in the charge-discharge cycle of the solid aluminum electrolytic capacitor. And meanwhile, cracks on the carbon layers on the surfaces of the carbon microspheres can be beneficial to insertion of electrolyte, so that the damaged oxide film in the production process is repaired to a certain extent.

Description

Technical Field

[0001] The invention relates to an aluminum electrolytic capacitor, and in particular to a solid aluminum electrolytic capacitor with good stability and a preparation method thereof. Background Art

[0002] Solid aluminum electrolytic capacitors have greater advantages in internal resistance and safety performance than liquid aluminum electrolytic capacitors; however, compared with liquid aluminum electrolytic capacitors, due to the lack of electrolyte to repair the oxide film, the leakage current of solid aluminum electrolytic capacitors is generally larger; In order to solve the problem that there is no electrolyte to repair the oxide film of solid aluminum electrolytic capacitors, current capacitor manufacturers generally impregnate a certain amount of electrolyte after forming a conductive polymer on the core package to correct the problem of anode foil damage caused during the production process; however, since a conductive polymer is formed in the core package, the amount of impregnated electrolyte is generally small; and since the conductive polymer is attached to the surface of the anode foil, it is difficult for the electrolyte to reach the vicinity of the damaged oxide film for repair, so the solid aluminum electrolytic capacitor impregnated with electrolyte is not very helpful in reducing leakage current. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a solid aluminum electrolytic capacitor with good stability and a preparation method thereof.

[0004] In order to solve the above technical problems, the technical solution proposed in the present invention is: a solid aluminum electrolytic capacitor with good stability, comprising a core package and a shell, the core package is sealed in the shell by a rubber plug, the core package is wound by an anode foil, a cathode foil and an electrolytic paper, and a conductive polymer is formed between the anode foil and the cathode foil, characterized in that: the conductive polymer comprises a first conductive polymer layer and a second conductive polymer layer, the first conductive polymer layer comprises a first conductive polymer and carbon microspheres wrapped with MnO2, the first conductive polymer wraps the carbon microspheres wrapped with MnO2; the weight of the carbon microspheres wrapped with MnO2 accounts for 1%-25% of the weight of PEDOT, the first conductive polymer comprises one of PEDOT and its derivatives; the second conductive polymer layer comprises one of PEDOT and its derivatives.

[0005] In the above-mentioned solid aluminum electrolytic capacitor with good stability, preferably, the carbon microspheres are in a core-shell structure, with the core being MnO2 and the surface being a carbon layer; the thickness of the surface carbon layer of the carbon microspheres is less than 2 μm.

[0006] In the above-mentioned solid aluminum electrolytic capacitor with good stability, preferably, cracks are present on the carbon layer on the surface of the carbon microspheres.

[0007] A method for preparing a solid aluminum electrolytic capacitor with good stability comprises the following steps: 1) adding carbon microspheres wrapped with MnO2 to a first conductive polymer and stirring evenly to form a first impregnation solution; 2) impregnating the core package with the first impregnation solution of step 1); and drying the core package to form a first conductive polymer layer on the core package; 3) impregnating the core package obtained in step 2) with a second impregnation liquid, wherein the second impregnation liquid comprises one of PEDOT and its derivatives; and drying the core package to form a second conductive polymer layer on the core package; In the above method for preparing a solid aluminum electrolytic capacitor with good stability, preferably, step 3) is repeated 2-5 times.

[0008] The above-mentioned method for preparing a solid aluminum electrolytic capacitor with good stability, preferably, the method for preparing carbon microspheres wrapped with MnO2 comprises the following steps; ① Carbonize sucrose and then wash it with deionized water to obtain black carbon microspheres; ② Add the black carbon microspheres in step ① into a saturated potassium permanganate aqueous solution, stir evenly, and let stand for 1-5 hours; ③ Filter the potassium permanganate aqueous solution in step ② to obtain carbon microspheres wrapped with potassium permanganate, and wash with deionized water to remove the solution on the surface of the carbon microspheres; ④ Add the carbon microspheres from step ③ into the aqueous solution of hydrogen peroxide and let stand for 1-5 hours; ⑤ Filter the solution of step ④, wash and dry to obtain carbon microspheres wrapped with MnO2.

[0009] In the above-mentioned method for preparing a solid aluminum electrolytic capacitor with good stability, preferably, the weight concentration of the hydrogen peroxide is 10%-30%.

[0010] In the method for preparing the solid aluminum electrolytic capacitor with good stability, preferably, after the step 3) is completed, the core is immersed in electrolyte.

[0011] Compared with the prior art, the advantages of the present invention are: in the present invention, carbon microspheres wrapped with MnO2 are added to the first conductive polymer layer, which can play a supporting role in the charge and discharge cycle of the solid aluminum electrolytic capacitor, thereby effectively preventing the conductive polymer from peeling off from the surface of the anode foil, thereby affecting the extraction of the capacitor. At the same time, the cracks on the carbon layer on the surface of the carbon microspheres can help insert the electrolyte, thereby repairing the damaged oxide film in the production process to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a scanning electron microscope image of the carbon microspheres in Example 1. DETAILED DESCRIPTION

[0013] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0014] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.

[0015] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Example

[0016] A solid aluminum electrolytic capacitor with good stability, including a core package and a shell, the core package is sealed in the shell by a rubber plug, the core package is wound by an anode foil, a cathode foil and an electrolytic paper, a conductive polymer is formed between the anode foil and the cathode foil, the conductive polymer includes a first conductive polymer layer and a second conductive polymer layer, the first conductive polymer layer includes a first conductive polymer and carbon microspheres wrapped with MnO2, the first conductive polymer wraps the carbon microspheres wrapped with MnO2; the weight of the carbon microspheres wrapped with MnO2 accounts for 20% of the weight of PEDOT, and in other embodiments, the weight of the carbon microspheres wrapped with MnO2 can be any value of 1%-25% of the weight of PEDOT, such as 5%, 10%, 15%, etc. In this embodiment, the first conductive polymer layer is PEDOT; the second conductive polymer layer is PEDOT:PSS, and the molar ratio of PEDOT:PSS is generally 4:1; In this embodiment, if Figure 1 As shown, the carbon microspheres have a core-shell structure, with the core being MnO2 and the surface being a carbon layer; the thickness of the carbon layer on the surface of the carbon microspheres is less than 2 μm; and there are cracks on the carbon layer on the surface of the carbon microspheres.

[0017] In this embodiment, the first conductive polymer layer is PEDOT, and the second conductive polymer layer is PEDOT:PSS, a derivative of PEDOT; thus, the first conductive polymer layer and the second conductive polymer layer can be effectively combined together.

[0018] In this embodiment, the first conductive polymer layer is attached to the surface of the anode foil, and the cracks on the carbon layer on the surface of the carbon microspheres enable the electrolyte to be quickly inserted and quickly moved to the location of the damaged oxide film on the surface of the anode foil for repair; in this embodiment, the MnO2 wrapped in the carbon microspheres can provide active sites for the electrolyte to undergo electrochemical reactions.

[0019] This embodiment also provides a method for preparing a solid aluminum electrolytic capacitor with good stability, which is characterized by comprising the following steps: 1) Adding carbon microspheres wrapped with MnO2 into a first conductive polymer and stirring the mixture evenly to form a first impregnation solution.

[0020] In this embodiment, the preparation method of carbon microspheres wrapped with MnO2 includes the following steps: ① Carbonize sucrose and then wash it with deionized water to obtain black carbon microspheres; ② Add the black carbon microspheres in step ① to a saturated potassium permanganate aqueous solution, stir evenly, and let stand for 3 hours. The standing time can be selected according to actual needs, generally 1-5 hours; ③ Filter the potassium permanganate aqueous solution in step ② to obtain carbon microspheres wrapped with potassium permanganate, and wash with deionized water to remove the solution on the surface of the carbon microspheres; ④ Add the carbon microspheres from step ③ to the aqueous solution of hydrogen peroxide and let it stand for 3 hours; the weight concentration of hydrogen peroxide is 20%. The time for the carbon microspheres to stand in the hydrogen peroxide solution and the weight concentration of hydrogen peroxide can be selected according to actual needs.

[0021] ⑤ Filter the solution of step ④, wash and dry to obtain carbon microspheres wrapped with MnO2.

[0022] 2) The core package is impregnated with the first impregnation liquid of step 1); and dried to form a first conductive polymer layer on the core package. The solvent of the first impregnation liquid can be a polyol, generally a solvent of a liquid aluminum electrolytic capacitor electrolyte, such as one or more of ethylene glycol, ethanol, propylene glycol, and glycerol.

[0023] 3) The core package that has completed step 2) is immersed in the second impregnation liquid to form a second conductive polymer layer on the core package; step 3) is repeated 2-5 times to form a sufficient PEDOT:PSS film in the core package. The second impregnation liquid is a dispersion of PEDOT:PSS, and the solvent of the dispersion can be a polyol, generally a solvent of a liquid aluminum electrolytic capacitor electrolyte, such as one or more of ethylene glycol, ethanol, propylene glycol, and glycerol.

[0024] 4) Impregnation with electrolyte. In this embodiment, the electrolyte used for impregnation is preferably an electrolyte with a relatively low viscosity.

[0025] In the present invention, carbon microspheres wrapped with MnO2 are added to the first conductive polymer layer, which can play a supporting role in the charge and discharge cycle of the solid aluminum electrolytic capacitor, thereby effectively preventing the conductive polymer from peeling off from the surface of the anode foil, thereby affecting the extraction of the capacitor. At the same time, the cracks on the carbon layer on the surface of the carbon microspheres can help insert the electrolyte, thereby repairing the damaged oxide film in the production process to a certain extent.

[0026] Comparative Example 1 In Comparative Example 1, the core package is only impregnated with the PEDOT:PSS dispersion liquid for 2-5 times, but not impregnated with the first impregnation liquid; that is, only a PEDOT:PSS film is formed in the core package; the rest is the same as in Example 1.

[0027] 20 48V, 240μF solid aluminum electrolytic capacitors of Example 1 and Comparative Example 1 were selected respectively; the initial capacity, internal resistance, leakage current, and average value of capacitance retention rate after 10,000 cycles were tested respectively; the results are as follows: .

Claims

1. A solid aluminum electrolytic capacitor with good stability, characterized by: The invention comprises a core package and an outer shell, wherein the core package is sealed in the outer shell by a rubber plug, the core package is wound by an anode foil, a cathode foil and an electrolytic paper, a conductive polymer is formed between the anode foil and the cathode foil, and the invention is characterized in that: the conductive polymer comprises a first conductive polymer layer and a second conductive polymer layer, the first conductive polymer layer comprises a first conductive polymer and carbon microspheres wrapped with MnO2, the first conductive polymer wraps the carbon microspheres wrapped with MnO2; the weight of the carbon microspheres wrapped with MnO2 accounts for 1%-25% of the weight of PEDOT, the first conductive polymer comprises one of PEDOT and its derivatives; the second conductive polymer layer comprises one of PEDOT and its derivatives.

2. The solid aluminum electrolytic capacitor with good stability according to claim 1, characterized in that: The carbon microspheres are in a core-shell structure, with a core of MnO2 and a surface of a carbon layer; the thickness of the surface carbon layer of the carbon microspheres is less than 2 μm.

3. The solid aluminum electrolytic capacitor with good stability according to claim 2, characterized in that: There are cracks on the carbon layer on the surface of the carbon microspheres.

4. The method for preparing a solid aluminum electrolytic capacitor with good stability according to any one of claims 1 to 3, characterized in that: The steps include: 1) adding carbon microspheres wrapped with MnO2 to a first conductive polymer and stirring evenly to form a first impregnation solution; 2) impregnating the core package with the first impregnation solution of step 1); and drying the core package to form a first conductive polymer layer on the core package; 3) The core package obtained in step 2) is immersed in a second impregnation liquid, wherein the second impregnation liquid comprises one of PEDOT and its derivatives; and dried to form a second conductive polymer layer on the core package.

5. The method for preparing a solid aluminum electrolytic capacitor with good stability according to claim 4, characterized in that: Repeat step 3) 2-5 times.

6. The method for preparing a solid aluminum electrolytic capacitor with good stability according to claim 4, characterized in that: The method for preparing carbon microspheres wrapped with MnO2 comprises the following steps: ① Carbonize sucrose and then wash it with deionized water to obtain black carbon microspheres; ② Add the black carbon microspheres in step ① into a saturated potassium permanganate aqueous solution, stir evenly, and let stand for 1-5 hours; ③ Filter the potassium permanganate aqueous solution in step ② to obtain carbon microspheres wrapped with potassium permanganate, and wash with deionized water to remove the solution on the surface of the carbon microspheres; ④ Add the carbon microspheres from step ③ into the aqueous solution of hydrogen peroxide and let stand for 1-5 hours; ⑤ Filter the solution of step ④, wash and dry to obtain carbon microspheres wrapped with MnO2.

7. The method for preparing a solid aluminum electrolytic capacitor with good stability according to claim 6, characterized in that: The weight concentration of the hydrogen peroxide is 10%-30%.

8. The method for preparing a solid aluminum electrolytic capacitor with good stability according to claim 4, characterized in that: After step 3) is completed, the core is immersed in electrolyte.

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